Tens of millions of people in the United States alone suffer from chronic pain, which may be loosely described as pain that lasts longer than three to six months. Chronic pain can be mild or excruciating, episodic or continuous, merely inconvenient or totally incapacitating. Signals of pain may remain active in the nervous system for weeks, months, or even years. This can take both a physical and emotional toll on a person. Common sources of pain include headaches, joint pain, pain from injury, and backaches. Other kinds of chronic pain include tendinitis, sinus pain, carpal tunnel syndrome, and pain affecting specific parts of the body, such as the shoulders, pelvis, and neck. Generalized muscle or nerve pain can also develop into a chronic condition.
Chronic pain may originate with an initial trauma/injury or infection, or there may be an ongoing cause of pain. However, some people suffer chronic pain in the absence of any past injury or evidence of body damage. Traditional pain drugs often to fail to quell neuropathic pain, particularly when the underlying source of the pain is due (at least in part) to the dysfunction of glial cells. Gilal cells are typically non-neuronal (non-excitable) cells that are associated with neurons. Glia typically far outnumber neurons in the spinal cord and brain, and are believed to maintain chemical environment surrounding neurons. Glia have been found to release pro-inflammatory cytokines to fight infection and initiate healing but can prolong the state of neural sensitization.
Pain is one disorder recently suspected to be mediated in part by cytokines. Pain mediated by cytokines is believed to result in pain that is far out of proportion to the minuscule tissue damage resulting from the injury (such as a splinter). It is believed that over-sensitized neurons fire wildly, which may send glia into a reactive state, in which the glia produces a cytokine cascade. The effect and sensation of the resulting pain (and the resulting cascade) may contribute to pain. For example, this cascade may result in chronic pain.
In addition, current pain treatment methods and systems may require increasing larger and more frequent dosages or treatments in order to remain effective, and may eventually diminish or stop being completely effective. For example, electrotherapy may be used to treat pain. Electrotherapy, which may also be referred to as spinal cord stimulation, typically involves the treatment of pain by providing electrical stimulation of spinal nerves to provide relief from pain. Spinal cord stimulators are devices that may be used to treat chronic pain by providing pulsed electrical signals to the spinal cord to control chronic pain. One example of spinal cord stimulation (SCS) consists of stimulating electrodes, implanted in the epidural space, an electrical pulse generator, implanted in the lower abdominal area or gluteal region, conducting wires connecting the electrodes to the generator, and the generator remote control. SCS has notable analgesic properties and, at the present, is used mostly in the treatment of failed back surgery syndrome, complex regional pain syndrome and refractory pain due to ischemia.
A spinal cord stimulator may generally include a pulse generator with remote controls, one or more implanted stimulating electrodes, and conducting wires connecting the electrodes to the generator. The electrodes for SCS are typically inserted in the patient's epidural space and may be anchored in position if the pain relieving effect is satisfactory after some test period. The electrodes (“leads”) may be anchored to the interspinal ligaments and connected (e.g., by tunneling) by connecting wires to the generator. The electrodes, which typically consist of an array of leads, could be percutaneous type or paddle type.
The other components, such as the pulse generator (e.g., an implantable pulse generator or IPG), may be implanted in the body. The pulse generator could be a complete pulse generator module with its own battery, or could have only a radio frequency (RF) receiver. A patient may also provided with a remote control to turn on and off the stimulator or change the programming of the stimulation patterns, of the programming patterns could be controlled by the medical practitioner. Various current, voltage and waveforms configurations of spinal cord stimulators are possible. Spinal cord stimulators come in constant current, variable voltage or constant voltage, variable current variations. The IPG is usually implanted in the lower abdominal area or in the posterior superior gluteal region.
Other methods for the treatment of chronic pain may include the use of pharmaceutical pain therapies such as opioids (or other narcotics), including the use of implants for the release of such drugs (e.g., drug pumps), and transcutaneous electrical nerve stimulation (TENS).
Herein we propose methods and systems for use with pain management therapies to treat chronic pain. In particular, the methods as devices described herein may be used in conjunction a pain management system such as those described above like SCS, opioid therapy, and TENS, to treat chronic pain. Thus, it is one goal of the present invention to provide a co-treatment with existing chronic pain therapies.
Although the NCAP pathway has been previously described and illustrated for modulation of inflammation, the concurrent use of NCAP therapy with other chronic pain management therapies such as SCS has not been previously suggested. This may be in part because it is unclear how simulation of NCAP (e.g., by simulation of vagus) would modulate or down regulate cytokines in the CNS, particularly by electrical means. Described herein are methods and systems for enhancing the treatment of chronic pain by modulation of the NCAP.